1. Field of the Invention
This invention relates to coating composition, in particular to polyurethane coating composition.
2. Description of the Prior Art
Ambient temperature curing compositions of a mixture of an acrylic and alkyd resin are shown in Miller and Walus, U.S. Pat. No. 3,585,160 issued June 15, 1971. An improvement to this composition that uses a polyisocyanate and catalyst is shown in Miller, U.S. Pat. No. 3,844,993 issued Oct. 29, 1974. Thermosetting coating compositions of an alkyd resin and an aliphatic polyisocyanate crosslinking agent are shown in Miller, U.S. Pat. No. 3,789,037 issued Jan. 29, 1974.
While the above compositions provide adequate finishes, none provide an isocyanate free polyurethane coating composition that forms a finish that cures at ambient temperatures that is useful for automobiles and trucks and is weatherable for a long term.